Culliver, Jacobs not practicing; James returns

Running back Brandon Jacobs (knee) and cornerback Chris Culliver (undisclosed) are among those not practicing today. Running back LaMichael James (knee) returned to practice, and he is participating in the padded proceedings.

— Sight of the day: Linebacker Patrick Willis collided with fullback Anthony Dixon during a one-on-one blocking drill, knocked back Dixon and ran around him for a sack.

On another head-to-head matchup, rookie tight end Garrett Celek held off Willis, with Willis unable to make much penetration. Impressive stuff for the youngster.

“We’re looking to see who our third, fourth and possibly fifth safety (are) and we need for that to clear itself up,” Fangio said. “And hopefully guys will step forward and make it easy. Right now, it hasn’t been an easy decision for us there.”

— The third exhibition game is when teams tend to give their projected starters their most extensive playing time. Even so, Fangio said, that doesn’t mean that the 49ers will spend much time game-planning for what the Denver Broncos offense does Sunday.

“The whole idea for training camp and preseason is to prepare your team for the regular season,” Fangio said. “That is the process we are going through. All during these weeks, we just keep hitting our guys with stuff that we know is going to be valuable during the season, put them in situations, see different plays, etcetera. We are working to get ready for the regular season.”

— The 49ers carried three inside linebackers last season. In a perfect world, Fangio said, this year’s roster will feature four.

“Ideally we would like to have it,” Fangio said. “Doesn’t mean we will, but ideally we would like to.”

— Defensive tackle Ray McDonald received considerably more playing time last season than he had the year before. Fangio said McDonald deserves credit for preparing himself the proper way for the increased workload.

“First off, he was in tremendous shape,” Fangio said. “I can’t comment on what kind of shape he was in prior to last year. Two, he was really developed as a player. Talking to the people that have been here throughout his career, he had his best season last year.

“Some guys, you never know when they’re going to make their big spike in their career. Sometimes it’s between year one and two,year two and three. Sometimes it’s later. But the guy is definitely one of the better interior linemen in the league. He’s a very valuable, valuable player to us.”